* {
    margin: 0;
    padding: 0;
  }
  @media screen and (min-width: 320px) {
    html {
      font-size: 21.33PX;
    }
  }
  @media screen and (min-width: 720px) {
    html {
      font-size: 50PX;
    }
  }
  div {
    width: 2rem;
    height: 2rem;
    background: blue;
  }
